Orthodontic arch

ABSTRACT

The present invention relates to an orthodontic arch ( 12 ) comprising at least one special loop ( 22 ) in the form of a spring hook. Said spring hook makes it possible to effect intrusion and corporal retraction of the front teeth, especially in the upper jaw, in a faster, more gentle and better controlled manner in comparison with conventional arches and methods. By additionally attaching rubber bands, springs or ligatures ( 24 ), all disadvantages of conventional constructions can be eliminated or minimized by means of an adjustable lever action effect due to the fact that the inventive arch-spring construction enables dynamic undulating movement of the front teeth adapted to biological processes during an activation procedure as opposed to conventional rigid mechanisms. Especially medical or biological requirements and aspects are fulfilled by the inventive arch. The inventive arch enables faster movement and greatly reduces damage and pain. In addition, the costs are lowered considerable by reducing the number of arches and by saving time.

The present invention relates to an orthodontic arch for making it inparticular possible to effect intrusion and corporal retraction of frontteeth, especially in the upper jaw, in a faster, more gentle and bettercontrolled manner as compared to conventional arches and methods.

Orthodontics is a treatment method in dental orthopedics in which rigidappliances are used. Brackets/tapes having specific slots are applied tothe teeth in the upper and lower jaws. In the Edgewise technique,preferably rectangular slots having specific dimensions and angles areprovided for this purpose. So-called arches, preferably made of squarewires, are inserted in the slots; along these wires or by means of thesewires a torsion or angulation imparts forces to the teeth in order tobring them into a different position. A specific and difficult problemin dental orthopedics regularly occurs in case of a so-called “deepbite” in which the upper front teeth bite vertically considerably overthe lower front teeth. For a correction, the upper front teeth have tobe intruded vertically, i.e. they have to be pushed again back into thejaw.

A mere intrusion, however, is rarely necessary; rather, in most casesalso especially the roots of the front teeth have to be moved in thedistal direction, i.e. towards the back. For this purpose, the frontteeth are preferably tilted by a distortion of the square arch, whereinthe point of rotation is located in the slot. This is also calledtorque. If the square arch is distorted much, the torque normally causesan extrusion of the front, i.e. exactly the opposite of the desiredmovement.

An even larger degree of difficulty is caused if extraction gaps, e.g.of the teeth Nos. 4 and 5 have to be closed, wherein at the same timefront teeth have to be intruded and the roots of the front teeth have tobe moved corporally in the distal direction, since an even strongertorque is required for this purpose, which means at the same time anincreased extrusion.

It is pointed out in general that the individual teeth in the upper andlower jaws are enumerated from the center (mesial) towards the back(distal), wherein it is in each case started with “1”. The archaccording to the present invention, which is described in the following,is preferably but not necessarily realized such that it can be used fora similar, symmetrical treatment of both sides of the respective jaw.

Normally, first the canine teeth are moved in the distal direction alonga continuous arch or along partial arches, thereby using loops, if,e.g., the teeth Nos. 4 or 5 are extracted, wherein the rear teeth (e.g.,the teeth Nos. 5 and/or 6) are used as an anchorage. If the teeth No. 3are in the respective positions of the original teeth No. 4, arelatively large gap has been generated in the distal direction of theteeth No. 2. The front, i.e. the teeth Nos. 1 and 2, are then commonlydrawn backwards in one block. Thus, the above-mentioned vertical andangulation problems are caused in connection with anchorage problemsfrom distal to mesial. In concrete terms, the rear anchorage teeth movetoo much towards the front.

This movement of the four front teeth, sometimes also of the six frontteeth, in the distal direction is partially carried out by means ofcontinuous arches to both sides of which one vertical hook is soldered.At this vertical hooks additional forces are applied by means of rubberbands which are anchored for the second time at the teeth No. 6 in theupper jaw or in the counter jaw. An example of such a conventionalarrangement is shown in FIG. 1. This arrangement to which hooks aresoldered or screwed is a very rigid system which is a biological andcauses considerable damage. Moreover, extreme anchorage losses arecaused and it is difficult to estimate the ideally applicable forcesand/or the forces being practically actually applied.

In a second conventional form of distalization of the front teeth, asquare arch having vertical loops (so-called bulloops) in the distaldirection of the teeth Nos. 2 or 3 is used. Such an arch is shown, forexample, in DE-C-35 24 714. These loops act as a spring and are firstclosed and then opened by activation in order to cause a resilienttensile force. The “activation” preferably takes place by fixing thearch in the distal direction at the respective anchor tooth, e.g. theteeth Nos. 6 or 7. The tensile force applied by the resiliency of thespring takes the front teeth with it, as shown, for example, in FIG. 2.This arrangement and method is biologically better tolerable and moreelastic; however, due to the loops there is the disadvantages that themovement in the distal direction goes along with a very strong tiltingmovement of the crowns in the distal direction and that due to thestrong torque which is required also an extrusion of the upper frontteeth has to be expected, i.e. altogether a strong tilting of the crownsdownwards in the distal direction. As mentioned, these movements havenegative effects and must be counteracted by other arches. This meansthat additional time is necessary and thus additional costs arise.

The square orthodontic arches known from the prior art, e.g. fortreating the above-mentioned diseases, are all disadvantageous in thatthe rigid system tends to cause an overactivation and then the frontteeth have to be moved in a position which is unfavorable as regardsanchorage, comparable to a plough through the ground. The biologicaltissue is thus not offered the necessary rest phases.

U.S. Pat. No. 5,131,843 describes an orthodontic arch for impartingforces to teeth. The arch is essentially U-shaped and has a centralfront portion and a pair of rear portions extending at both sides of thefront portion. Moreover, the arch comprises a pair of T-loop elements,wherein one of the T-loop elements is provided at any side of the mesialcenter line. Each of the T-loop elements has a pair of legs which extendessentially vertically and are adjacent to each other and which form anessentially closed loop at its upper end. The upper cross-loop of theT-shape extends essentially parallel to the arch.

U.S. Pat. No. 5,092,768 relates to a removable appliance for distalizingthe lips or for keeping the lips away from the teeth. In order toprovide an as large as possible rest area for the lips, loops arebent-in in a wire. The wire is fixed at the two molars.

U.S. Pat. No. 4,412,819 describes an orthodontic arch with front andrear portions having a different elasticity and strength, wherein acentral portion made of a relatively resilient wire and rear portionsmade of a different and harder wire are formed. Moreover, differentcross-sectional shapes can be realized in the portions.

It is the object of the present invention to provide an improvedorthodontic arch which is particularly suitable for regulating theabove-described phenomena in a better way.

Thus, a system should be developed which is biological, flexible, fastand better controllable, widely avoids damages as well as exhibitsminimum anchorage losses.

For achieving this object, the invention starts out from the basic ideaof achieving the desired improved intrusion and torque movements bymeans of a novel lever system, so that minimum forces have to be appliedand the system is flexible. For this purpose, the arch comprises aspring hook which preferably extends obliquely to the arch direction.

It is an essential aspect of the present invention that a favorablemechanical force application (lever and at the same time spring) and notonly directly action-reaction is striven for, this interaction takinginto account the biological aspects more strongly. In medicine ingeneral and thus also in dental orthopedics, the biological factors suchas, e.g., blood supply play an important role in order to effect thedesired change as biologically, painlessly and quickly as possible. Ifthe blood supply is compressed, there is no movement since notransformation of the bone is possible due to the lack of blood. Thismeans that in the biological, living tissue the proportion betweenapplied force and achieved movement speed is practically reversed sincethe blood supply is reduced as the force increases. In the biologicalfield the biological relationships must thus be taken into considerationwhen physical laws are applied.

The arch according to the present invention can extend both along allteeth of the respective jaw and only along parts thereof, in particularin the front. If the arch is provided only in the area of the frontteeth, the anchorage is preferably provided in the area of the canineteeth.

In the following the invention is described on the basis of preferredembodiments by means of drawings in which

FIG. 1 is a prior art system with a continuous arch with verticallyattached hooks;

FIG. 2 is a prior art system with a continuous arch and bulloops;

FIG. 3 is an embodiment of the system of the present invention with asquare arch and rubber bands;

FIG. 4 is an embodiment of the square arch according to the presentinvention with opened spring;

FIG. 5 is a further embodiment of the square arch according to thepresent invention with a rubber band, a spring and a ligature;

FIG. 6 is a conventional straight, non-bent arch in which a front torqueand/or a strong angulation of the wire are bent in at the tooth No. 6;

FIGS. 7-13 are further embodiments of the arch according to the presentinvention;

FIG. 14 is a preferred embodiment of the spring hook;

FIG. 15 is a representation of the spring hook of FIG. 14 withdimensioning; and

FIGS. 16-17 show the preferred position of the spring hooks at the archaccording to the present invention including dimensioning.

The arrangements of FIGS. 1 to 3 show teeth 2-i in the upper jaw 2 andteeth 4-i in the lower jaw 4 of a patient. The extension “i” means i-thtooth in the upper or lower jaw according to the common definition basedon the mesial line. Each of the teeth 2-i and 4-i has a root area 6located in the jaw, as well as a crown 8 protruding therefrom.

To each of the crowns 8 of the teeth 2-i and 4-i preferably one bracket10 with a slot extending in the mesialdistal direction, i.e. sagitaldirection (shown only schematically) is attached. As already explainedabove, the slots are shaped such that a continuous arch 12 or severalindividual arches (not shown) are guided through them in order tointroduce together forces into the respective teeth 2-i and/or 4-i.

As already described above, a conventional kind of front toothretraction is given in that a vertical hook 14 is provided at thecontinuous arch 12. Rubber bands 15 are hooked in the vertical hook 14,said rubber bands 15 having their second anchorage 16, e.g., at theteeth Nos. 6, 2-6 in the upper jaw and/or 4-6 in the counter jaw.

For displacing the front teeth 2-1, 2-2 and optionally 2-3 in the upperjaw and the front teeth 4-1, 4-2 and optionally 4-3 in the lower jaw(for symmetrical reasons it is preferred on both sides), the entire arch12 must be displaced through all brackets 10 in the side area. Thismeans that the arch 12 must be displaced through the brackets 10 locatedon the teeth 2-5, 2-6 and 2-7 as well as 4-5, 4-6 and 4-7. In order toachieve this, strong forces are required, in particular for overcomingthe strong frictional forces and the “plough angulation” of the frontteeth (point of rotation in the slot=corporal movement). The strongforces in turn cause a considerable loosening and damage at the toothtips (in up to 65% of the cases) of especially the anchoring teeth andthe front teeth as well as strong pain and slower movements due tocompression of the blood supply, which leads to strong anchoring losses.This is synonymous with an undesired tilting of the crowns of theanchorage teeth in the mesial direction. As shown in FIG. 6, an elastictorque of the arch in the area of the teeth Nos. 4 and 5 towards the topis thus increased, which is also additionally caused and increased by anecessary active torque in the front; this additionally causes a strongfriction. This could be reduced if the hooking appliance 14 is arrangedat a somewhat higher position; however, in the conventional rigid systemthis would at the same time increase friction and the anchorage problemsdue to the lever mechanism, and thus hinder the desired passing-throughof the arch since friction is caused by the lever.

The appliance shown in FIG. 2 for a distalization of the front teeth2-1, 2-2, 2-3 and/or 4-1, 4-2 and 4-3 is based on the appliancedescribed above. However, instead of the hooks 14, the counterattachment positions 16 and the rubber bands 15, so-called bulloops 18are arranged in the distal direction of the teeth Nos. 2 or 3, i.e. 2-2,2-3 and/or 4-2, 4-3. A bulloop 18 is a loop which is providedessentially vertically with respect to the mesial-distal direction ofthe arch 12. The loops represent a spring which, when trying to closeitself, takes the front teeth with it in the distal direction. Thebulloops 18 or the springs are mounted in the closed state and thenactivated in order to impart their forces. For the purpose ofactivation, a so-called tieback loop 20, which activates the bulloops 18when being provided on the teeth Nos. 7, i.e. 2-7 or 4-7, is providedbetween the teeth Nos. 6 and 7, i.e. 2-6 and 2-7 or 4-6 and 4-7. Thisappliance or this method have the considerable disadvantage that themovement in the distal direction goes along with a strong tiltingmovement of the crowns 8 of the upper front teeth downwards in thedistal direction and, due to the necessary strong torque, also anextrusion of the front teeth is caused. As already explained above,these movements must be regulated later by means of different arches.

In the appliance according to the present invention as exemplarily shownin FIG. 3, the disadvantages known from the prior art are avoided orminimized. This is particularly due to an improved control of theintrusion and torque movements which is achieved by a novel spring andlever system.

The invention is based on the idea of providing the arch 12 with atleast one special “spring hook” 22, which can also be called a loop orspring 22, preferably in the front. In contrast to known bulloops, thespring hook 22 is bent or forms an angle and has at least one part whichdoes not extend vertically and/or parallel to the arch 12. The springhook 22 is preferably bent several times, e.g. bent two times. Thus, thespring hook 22 can impart force components having different directionsand strengths to the teeth and can act in different partial areas as apressure and/or tension spring. The spring hook 22 is preferablyattached in the closed state. A slight drawing-through of the rear partof the arch 12 and subsequent attachment to the anchor tooth leads tothe opening of the spring hook 22 and its activation. Due to itsgeometric construction and position (cf., for example, FIGS. 4, 5 and 7to 9), the spring hook 22 imparts an intrusion force to the front teethand thus causes a counter force to the extruded components in the front.The spring hook 22 is preferably located in the area at the distal sideof the teeth Nos. 2 or 3 and at the mesial side of the teeth Nos. 4 or5. This approximately corresponds, e.g., in an area extending from themesial line in the distal direction about 10% to 50% of the length ofthe arch 12 from the mesial line or center of the arch to the distal end(10% to 50% of the length of half of the arch). The presently preferredposition of the spring hook 22 is shown in more detail in FIGS. 16 and17. In accordance therewith, with a radius of the arch of about 27 mm(1.0625 Inch) the spring hooks 22 are located in the area of the frontteeth about 75° away from the mesial line or center of the arch.

As an alternative, for activating the spring hook 22 a tieback loop 20with a ligature can also be provided and fixed to the respective anchortooth.

For providing an active torque for the distalization of the roots 6 inthe area of the front teeth, the arch 12 is, for example, distorted inthe front. Due to this bend, the torque will also simultaneously drawthe crowns 8 of the front teeth in the distal direction due to a centerof rotation which adapts itself depending on the course of movements, ascompared to conventional techniques. Thus, since the spring hook 22 isshaped in accordance with the present invention, the point of rotationcan move from the slot to the tip of the root or vice versa, dependingon the treatment situation. During a course of activation or movements,the arch construction according to the present invention, which can alsobe understood as a spring construction, first more or less yieldsdifferent moments, depending on the thickness of the wire and thetorsion. This is more favorable in a biological and vectorial sense formoving the upper front teeth upwards in the distal direction. In thisconnection, it must be taken into consideration that during its sagitalactivation the construction according to the invention at the same timecauses a vertical intrusion component. Due to the lighter forces and thecenter of rotation which adapts itself, the blood supply is maintainedto a large extent; this means a faster movement as compared toconventional systems. Thus, a determined and corporally displaced endposition of the front teeth is achieved due to slight adaptive,undulating or tilting movements during the course of movements.

In conventional arrangements and methods, in particular according toFIG. 1, the point of rotation always remains in the center of the slot,so that the front teeth are moved through the bone like ploughs. In thearrangement according to FIG. 2, the point of rotation can even movedown into the tips of the roots, depending on the thickness of the wire,and can lead to the fact that the crowns 8 are mainly tilted downwardsin the distal direction, i.e. are extruded. In contrast thereto, theconstruction according to the present invention is a flexible systemwhich causes a displacement of the point of rotation, depending on thepast movement of an activation process from the bottom to the top andback, since against the sagital activation and against the extrudingtorque forces always a vertical moment is included in the loop 22, e.g.by a bend.

In order to increase the vertical and sagital component, the spring hook22 is formed for simultaneously hooking in rubber bands 24, springs orligatures. Thus, in addition to intrusion components, also lever momentswith a minimum sagital force can be used. This embodiment of theappliance according to the present invention is shown in more detail inFIGS. 3, 5 and 13. Depending on the application, the rubber bands 24,springs or ligatures can be fixed at the same and/or opposite jaw.Preferably, the rubber bands 24, springs or ligatures are, on the onehand, fixed at the spring hook 22 and, on the other hand, at an end 26of the arch 12 which projects from the tieback loop 20. Depending on theposition of the anchoring end, more sagital forces or more verticalforces are caused.

By means of the appliance according to the present invention, preferablya so-called deep bite can be regulated, but also only an angulationand/or extrusion can be caused. In this connection, no undesiredfriction occurs, the vertical components are clearly supported and theoriginal arch shape is stabilized. Moreover, only very slight anchoringproblems occur; thus, very purposeful movements and above-averagemovement speeds of the teeth can be caused. This is particularly due tothe fact that the appliance according to the present invention is anabsolutely flexible and biologically oriented system.

FIG. 6 shows a conventional straight, non-bent (non-broken) arch in theactivated state in which a front torque and/or a strong angulation ofthe wire is/are bent in at the tooth No. 6. In the area 28 of the teethNos. 3, 4 and 5 there are conventionally strong vertical elastic bends,which are undesired. This elastic deformation can be counteracted by abent-in bend in the arch, as shown in FIG. 5; then it could, however, bepresent more intensively in the area of the loop 22. This negativecounter effect can be counteracted by stronger angulation bends at thespring hook and/or by hooking in a rubber band 24 or a ligature from theloop 22 to the teeth Nos. 6 or 7, wherein additionally a gap closuremovement is integrated. In the prior art system shown in FIG. 1, thiselastic or also plastic bend would in any case cause additionallyconsiderable friction problems.

In a different embodiment of the present invention as shown in FIG. 4, aheight difference h between the legs of the arch 12 can be provided inorder to locally include additionally vertical force components actingon the teeth.

The appliance according to the present invention can be used in adifferentiated manner in all three dimensions and operated individuallyand flexibly, corresponds to the biological requirements as regardsforce, dimension and flexibility, causes a minimum anchorage loss (therear anchorage teeth do not move or move only slightly in the mesialdirection), and the above described disadvantages of conventionaltechniques are minimized or eliminated by means of the technique of thepresent invention.

The appliances according to the present invention can have differentarch sizes, loop sizes, loop positions, loop inclinations and wiredimensions and consist of different materials. The arches describedabove can be produced with or without tieback loops or similar loops.For example, the tieback loop 20 can be replaced in that slightly in thedistal direction of the last tooth, the arch is drawn through abracket/band 10 attached thereto and bent. Thus, the contraction spring22 could be activated as well.

The use of a tieback loop 20 is particularly advantageous in that due toa springing angulation the root of the tooth No. 7 can be held in themesial direction in a manner being favorable as regards anchorage, andthat due to the primary activation counter bends (vertical bends) can beprovided in the arch 12 since no friction losses occur.

Due to the realization of the arch 12 in accordance with the presentinvention, in particular an intrusion of the front teeth (teeth Nos. 1,2 and optionally 3) can be caused. For this purpose, the arch 12 canadditionally be pre-bent in the area of the teeth Nos. 3, 4 and 5, sothat during introduction into the slots of the brackets 10 and after asubsequent fixation therein, the arch 12 essentially extends in thesagital direction and thus causes an intrusion force component in thearea of the teeth Nos. 1, 2 and (optionally) 3 due to the tension causedby the bend. This prebent wire of the arch 12 as shown in FIG. 5 canpreferably be combined with the system which is shown in FIG. 4 anddescribed above.

In FIGS. 7 to 17 different embodiments of the arch 12 according to thepresent invention are shown exemplarily. Depending on the application,the spring hook 22 is formed with individual inclination angles a for afirst hook arm 30 and β for a second hook arm 32. With the same bendshape of the loop 22, the angle α decides about the load areas in thearea of the front teeth since the vertical link is, as shown in FIG. 7,more in the vertical area of the tooth No. 2 and less in the area of thetooth No. 1. In FIG. 8 the link is more in the area of the teeth Nos. 2and 1. Not only the inclination angle a but also the inclination angle pare decisive for more vertical counter forces against torque and tiltingof the crowns of the teeth Nos. 1 and 2 in the distal direction. Theseinclination angles and the forces resulting therefrom can be adjustedindividually, depending on the situation, by previously bending thewire, i.e. they can be “pre-bent”.

Also the position of the angulation of an upper loop area 34 isdifferent for vertical and sagital forces as well as for an easierhooking-in of rubber bands. For example, for a deep bite the embodimentshown in FIG. 8 is preferably more favorable. Bend areas 36 and 38formed at the spring hook 22 as well as all other bends or arches shouldpreferably be shaped continuously or bulgedly, in order to influence thesliding movement of the point of rotation uniformly.

As already explained above, the dimensions of the angles α and β can berealized in different manners, wherein they can be equal or different.Moreover, the angle α can also be not equal 180°−β and vice versa. Theopening angle γ of the spring hook 22 can, as shown in FIG. 9, varybetween 0° and 180°, preferably 0° to 90° or 30° to 90°. Moreover, alsothe inclination angle λ of the upper loop area 34 can be variable. Theangles γ and λ can moreover be different from each other. Preferably,the angles γ and λ lie in the range between 30° and 60°, more preferablybetween 40° and 50°, particularly preferably at about 45°.

On the basis of the above description of the embodiments according toFIGS. 7 to 9 it is clear that a plurality of shapes and positions of thespring hook 22 can be provided for the arch 12 according to the presentinvention. For example, the bends can have a circular, elliptical and/ordrop shape. Also edges and kinks can be provided. In addition to thehook shapes shown in FIGS. 7 to 9, the arch according to the presentinvention can have a plurality of further shapes. For example, the hook22 can have further bends in the upper area 34 or in the area oppositethereto, as shown in FIGS. 10, 11 and 13. According to FIG. 13, it is inparticular also possible to form a hook or a loop 40 in the bendprovided in the area 34 in order to attach rubber bands 24 or the likethereto. FIG. 12 shows an alternative, very bulged hook shape which isbent at an angle of about 180°.

The dimensions of the spring hook 22 can vary depending on theapplication. In particular the height and the position of the individualportions of the spring hook 22 can be varied depending on the purpose,whereby different lever arms and thus forces and moments can be impartedto the teeth to be regulated. By a combination of the different anglesand lengths of the spring hook 22, a plurality of shapes of the springhook 22 are possible.

A particularly preferred embodiment of the arch of the present inventionwith the spring hook 22 is shown in FIGS. 14 to 17. With reference toFIG. 14, first the individual portions of the spring hook are defined.The distance between the two summits A and B is called the loop lengthLL. The distance between the points C and D defines the base height BHof the spring hook 22. The distance connecting points B and F is thebase length BL. The total height of loop height LH of the spring hook 22and the total width or loop width LW is also shown in FIG. 14. Thesummits A and B also define the loop axis. In the preferred embodimentof the arch according to the present invention as shown in FIGS. 14 to17, the spring hook 22 is shaped such that the angle 1 has about 45°,wherein the angles 3 and 4 (or αand β) have 90°. The connection betweenthe points B and F, which defines the base of the loop, is formed inthis preferred embodiment with the angle 2 of about 10° to 20°. Thepoints A to G are preferably the intersections of the respective bends.

The dimensions of FIGS. 15 to 17 are indicated in Inch. According toFIG. 14, the thickness of the wire of the arch is 0.016 Inch (0.41 mm).The height of the spring hook 22 measured from the upper edge of thewire is 0.280 Inch (7.11 mm). The total width LW of the spring hook 22is 0.186 Inch (4.72 mm), wherein the head area of the spring hook 22forming the loop with the summit A is spaced by 0.111 Inch (2.82 mm)from the space between the foot legs 30 or 32. The two foot legs 30 and32 have a distance of 0.004 Inch (0.1 mm) from each other. The base,i.e. the line connecting the points B and F, is inclined by an angle ofabout 10° to 20° with respect to the horizontal line. The loop axisbetween the points A and B is inclined by an angle of about 45° so thatbetween the base and the loop axis there is an angle of, e.g., about65°. The radius in the area of the loop head, i.e. at the point A isabout 0.035 Inch (0.89 mm). The remaining radiuses formed in the area ofthe loop have a radius of about 0.020 Inch (0.51 mm).

As shown in FIG. 16, the radius of the arch in the area of the frontteeth is 1.0625 Inch (27 mm), wherein this circular bend is formed onboth sides of the mesial or center line of the arch along an angle of75°. Following both sides of the circular arch, respective essentiallystraight arch portions are provided which each open at an angle of about15°, whereby a total width of the arch of 2.834 Inch (72 mm) with atotal length of 3.016 Inch (76.6 mm) is formed.

The loop axis defined by the points A and B is essentially responsiblefor the elasticity of the system. Moreover, also the angle 2 isimportant for the elasticity of the loop during opening and closing,since depending on its dimensions more vertical or more transversalloads are directed to the point D or to distal parts. The smaller theangle 2 becomes, the larger is the vertical force component occurring inthe area of the point C; this is synonymous with an elasticityreduction. The point G is essentially the center of the loop and is inthe area between the points B and C; thus, mechanical forces aresupported for intruding the front during sagital opening and closingmovements. Also the point G is partially responsible for the elasticityof the loop. In the area of the point G there is essentially thestiffest point of the loop. Moreover, the point G is the starting pointfor a lever by means of which the front is moved. The height of thepoint G depends on length of the lever arm with regard to the frontteeth. The closer this point is with respect to the resistance center ofthe front teeth or a point above it, the lighter force is required for acorporal intrusion and distalization of the front teeth. The lower theanchorage losses are, the better can the intrusion, the torque and thecorporal displacements be controlled.

In the clinically non-activated state, the spring hooks 22 are closed atthe bottom, i.e. at the hook foot or the transition to the straightbend, as shown in FIG. 7, and can then be pre-tensioned or activated.

However, the spring hooks 22 can also be opened slightly, as shown inFIGS. 8 and 9, so that the spring can be activated or tensionedindividually due to an intensification of the loop shape at one of theplurality of desired positions, since a change in the loop shape of thespring hooks 22 at different positions causes different tensions.However, also the hook shape of spring hooks 22 which are closed attheir bottom can be changed individually.

Such spring hooks 22 then have, for example, only one basic shape forthe hook which can be further changed depending on the application.

The arch 12 according to the present invention provides better torqueand intrusion possibilities and minimizes or eliminates frictionproblems and anchorage losses. The arch 12 is a loop construction beingmade preferably of a stainless steel and having a square cross-section.Different wire sizes can be used (0.011×0.020; 0.012×0.020; 0.013×0.020Inch). The brackets 10 can, for example, have 0.016×0.020 Inch slots.Such slot sizes allow a very early use of a square wire with at the sametime very good control possibilities of all dimensions. The arch 12according to the present invention allows a very good handling, optimumconsideration of all biological aspects, integrates functional conceptsand leads to more individual results as compared to conventional arches.Different angulations or angles, variations in the direction of theforce and the shape of the spring hook 22 lead to a plurality ofdifferent possibilities in medical use. The spring hooks 22 of the arch12 according to the present invention are also very effective for biteopening and torque control. The patient can manage it easily and it isvery well accepted by him/her. The arch 12 according to the presentinvention is also more favorable with respect to the duration of thetreatment, the comfort, the biological efficiency and anchorage lossesas compared to conventional rigid systems.

The present invention provides a novel orthodontic arch havingconsiderable advantages. The loops known so far are either vertical orhorizontal loops. By means of the arch with spring hooks according tothe present invention, which comprises a defined loop axis (e.g. 45°),it is possible to combine the advantages of known loops and to avoid therespective disadvantages of conventional loops. Thus, strong extrusionresults in the front teeth, which are caused by torque and retraction,can be counteracted in a controlled manner. While the bulloop hasrelatively good contraction components, in this loop the verticalintrusion moments are very rigid and do not have a spring component. Thefront teeth tilt with the crowns in the distal direction and extrude. Inthis connection, the depth of the slot must be used as a lever armagainst the long roots in order to distalize and intrude the roots. TheT-loop, like the bulloop, has good vertical spring components; however,due to this property it is not a typical retraction spring. Moreover,due to the torque acting on the front, the front itself is extruded verymuch since this is not prevented by the spring, and during retractionthis extrusion is further supported. During activation and duringclosing of the T-loop, mainly non-controllable vertical moments arecaused; this moves the roots back and forth and thus damages andshortens the tips of the roots (resorption). Depending on the positionof the T-loop, the front teeth or the incisor teeth are extruded moreconsiderably. Thus, the T-loop is a poorly controllable spring foreffecting corporal retractions and intrusions of teeth. If rubber bandsare hooked in known systems, they immediately move into the bracketarea; this further supports the extrusion forces which should just beavoided.

These disadvantages are avoided in the arch according to the presentinvention with the spring hook with the definedly bent loop axis.Moreover, the loop in the arch according to the present invention hasthe further advantage that rubber bands or the like can be hooked in atabout the height of the point of rotation of the front teeth. Thispossibility is not given in the known loops. By means of the archaccording to the present invention, a reactive movement of the rearteeth in the mesial direction is counteracted effectively so that a verycontrolled movement in the area of the front teeth can be achieved bothin the vertical direction and the sagital direction. In the entiresystem of the invention very minimum forces can be applied; in the knownloops this is only possible if other disadvantages (e.g. bad control inthe vertical direction) are accepted.

What is claimed is:
 1. An orthodontic arch which can be introduced inbrackets being attached to teeth and at least portions of which extendin the sagital direction, wherein said arch is formed of a wire which isessentially prebent to an U-shape in the sagital direction and whichcomprises at least one spring hook in at least one area in a directiondiffering from the direction of the arch, wherein said spring hook isshaped such that it forms a loop axis (AB) which extends at an angle inthe range between 30° and 60° with respect to the sagital direction. 2.The arch according to claim 1, wherein at least one distal end of saidarch a loop for anchoring said arch at an anchorage tooth is provided.3. The arch according to claim 1, wherein the wire for anchoring thearch at an anchoring tooth is bent at least one end of said arch.
 4. Thearch according to claim 1, wherein said spring hook is shaped forhooking in a rubber band, springs or a ligature.
 5. The arch accordingto claim 4, wherein said spring hook is shaped such that a secondanchoring point of said rubber band, the spring or the ligature can beprovided in the area of the distal end of said arch.
 6. The archaccording to claim 5, wherein said spring hook is shaped such that thesecond anchoring point of said rubber band, the spring or the ligaturecan be provided between the distal end and said spring hook.
 7. The archaccording to claim 5, wherein said spring hook is shaped such that thesecond anchoring point of said rubber band, the spring or ligature canbe provided at the same and/or opposite part of the jaw.
 8. The archaccording to claim 1, wherein said spring hook is located in an area inthe distal direction of the teeth Nos. 2 or 3 and in the mesialdirection of the teeth Nos. 4 or 5, i.e. in an area of about 10% to 50%of half the length of said arch away from the mesial line or center ofthe arch.
 9. The arch according to claim 1, wherein in at least one areaalong said arch a pre-bent bend is provided in a direction differingfrom the sagital direction or arch direction.
 10. The arch according toclaim 1, wherein said essentially U-shaped arch has height differencesand/or a step in a direction extending essentially vertically withrespect to the direction of the arch.
 11. The arch according to claim 1,wherein said spring hook extends from said arch at a first inclinationangle a with a first hook arm and at a second inclination angle β with asecond hook arm.
 12. The arch according to claim 11, wherein said firstinclination angle a is essentially equal to said second inclinationangle β.
 13. The arch according to claim 11, wherein said firstinclination angle α is not equal to a complementary angle of 180° minussaid second inclination angle β or said second inclination angle β isnot equal to a complementary angle of 180° minus said first inclinationangle α.
 14. The arch according to claim 11, wherein said firstinclination angle α is equal to the complementary angle of 180° minussaid second inclination angle β or said second inclination angle β isequal to the complementary angle of 180° minus said first inclinationangle α.
 15. The arch according to claim 1, wherein said spring hook hasan opening angle γ in the range between 30° and 60°.
 16. The archaccording to claim 1, wherein an upper area of said spring hook isprovided at an inclination angle λ relative to said arch.
 17. The archaccording to claim 16, wherein said inclination angle λ is equal or notequal to said opening angle γ.
 18. The arch according to claim 17,wherein said inclination angle λ lies between 0° and 180°.
 19. The archaccording to claim 1, wherein said spring hook is closed in anon-activated state.
 20. The arch according to claim 1, wherein saidspring hook has a basic hook shape which can be further adaptedindividually.
 21. The arch according to claim 1, wherein said springhook comprises a plurality of portions which extend in differentdirections with respect to said arch.
 22. The arch according to claim 1,wherein said spring hook comprises at least one portion which does notextend vertically with respect to said arch.
 23. The arch according toclaim 1, wherein partial areas of said spring hook are shaped as apressure spring and/or tension spring.
 24. The arch according to claim1, wherein bends in said spring hook comprise portions having acircular, elliptical and/or drop shape.
 25. The arch according to claim1, wherein in an upper area of said spring hook at least one furtherbend is provided, said bend being shaped for hooking in a rubber band,springs or a ligature.
 26. The arch according to claim 1, wherein thewire is a square wire.
 27. The arch according to claim 1, wherein saidspring hook has a basis (BF) which is formed at an angle in the rangebetween 10° and 25° with respect to the sagital direction.
 28. Anorthodontic arch which can be introduced in brackets being attached toteeth and at least portions of which extend in the sagital direction,wherein said arch is formed of a wire which is essentially prebent to anU-shape in the sagital direction and which comprises at least one springhook in at least one area in a direction differing from the direction ofthe arch, wherein said spring hook has a basis (BF) which is formed atan angle in the range of between 10° and 25° with respect to the sagitaldirection, and wherein said basis comprises a guide on which an adjacentpart of the spring hook can move during opening and/or closing of thehook.
 29. The arch according to claim 28 wherein said spring hook isshaped such that it forms a loop axis (AB) which extends at an angle inthe range between 30° and 60° with respect to the sagital direction.